Atomic Number: 11
Atomic Mass: 22.990
Place in Periodic Table: Alkali Metal



sodiumsquare.gif
This Mendeleev square tells us that Sodium has an atomic number of 11, meaning that if the atom is balanced, it will have 11 electrons. the atomic mass of sodium is 22.99, which basically means that it is nearly 23, and so therefor 23-11= 12, so there are 12 neutrons in sodiums nucleus.
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